All this debate about whether someone was or wasn't the other woman is interesting and everything. And in the long run, I hope it becomes irrelevant and unimportant. But in the moment, when it is discovered, all that becomes white noise. There is only one person who can define the nature of that "relationship".
Of course the husband will spin it to relieve his guilt. And his paramour can't usually think of herself that way because what does it say about how he is going to treat her in the future?
The wife is who gets to define whether her husband has been unfaithful.
Go ahead and get married and live happily ever after but respect the woman whose world was just turned upside down. It really is the least you can do.
Am I crazy?